This invention relates to a hollow trilobal cross-section filament for use as carpet yarn, and to a spinnerette for its manufacture.
Trilobal filaments with at least one axially extending hole are described in U.S. Pat. Nos. 3,493,459, 4,001,369, 4,648,830 and 4,770,938. U.S. Pat. No. 4,770,938 describes a trilobal filament having an axially extending hole in each lobe. The total cross-sectional area of the filament is 5 to 12 percent void, the filament cross-section has a modification ratio of 2 to 3 and an arm angle of 15.degree. to 45.degree.. U.S. Pat. No. 3,493,459 describes a trilobal filament having an axially extending hole at the center of the filament and smaller axially extending holes in each lobe.
Although the prior art hollow filaments are said to provide improved sparkle or luster and bulk when used as a carpet yarn, there exists a need for further improvement in these properties. In addition, it would be advantageous if hollow filaments could improve the cover of carpet yarns.